In recent years, various kinds of wireless communication devices including a wireless LAN (Local Area Network) are mounted in all sorts of apparatuses such as personal computers, peripheral devices, cellular phones, video game machines, and home electric appliances. Especially, a mobile apparatus such as a notebook computer, cellular phone, or video game machine sometimes moves while using an application. An easily imaginable situation is, for example, a user's moving while calling using a cellular phone.
In moving while keeping wireless communication, the wireless communication terminal may move out of the coverage area of the wireless base station of communication target, or switch the base station of communication target upon detecting the presence of a base station in a better radio wave state based on information sent from wireless base stations. For example, assume that a plurality of connection destination base station candidates exist simultaneously. If the received field strength of the currently connected base station falls below a predetermined threshold, base station switching processing occurs to reconnect the wireless communication terminal to a base station with a stronger received field. The switching processing that occurs at this time is generally called handover.
Occurrence of handover brings about the following situation. Until the wireless communication terminal starts IP (Internet Protocol) data communication with a network via a base station, negotiation and IP setting processing for connection via a wireless layer are necessary. For example, when a dynamic setting method such as DHCP (Dynamic Host Configuration Protocol) is used for the IP setting processing, the wireless communication terminal and the DHCP server normally exchange several packets.